1. Field
The present disclosure relates to a fuel cell stack.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell includes a membrane electrode assembly (MEA) and a pair of separators sandwiching the MEA therebetween. The MEA includes an electrolyte membrane, which is made from a solid polymer ion-exchange membrane, an anode separator disposed on one side of the electrolyte membrane, and a cathode electrode disposed on the other side of the electrolyte membrane. Usually, a plurality of fuel cells are stacked so as to form a fuel cell stack. The fuel cell stack is, for example, mounted on a fuel-cell electric vehicle and used as an automobile fuel cell system.
A fuel cell stack includes a stacked body in which a plurality of fuel cells are stacked; and a terminal plate, an insulator, and an end plate that are stacked at each end of the stacked body in the stacking direction. For example, Japanese Patent No. 4727972 describes a fuel cell stack in which a so-called dummy cell is disposed on at least one end portion of a stacked body in the stacking direction. The dummy cell, which has the same structure as a fuel cell, is disposed between the stacked body and a terminal plate. The dummy cell includes a metal plate instead of an electrolyte membrane and does not generate water because the dummy cell does not generate electric power. Therefore, the dummy cell functions as a heat insulating layer.
A type of fuel cell stack having a skip cooling structure is known. The fuel cell stack includes a plurality of power generation units each including a first separator, a first electrolyte electrode assembly, a second separator, a second electrolyte electrode assembly, and a third separator that are stacked in this order; and a coolant channel through which a coolant flows is only formed in each of spaces between the power generation units.
In the fuel cell stack having a skip cooling structure, the cooling conditions of the first electrolyte electrode assembly and the second electrolyte electrode assembly that are disposed at ends in the stacking direction differ from those of the first electrolyte electrode assembly and the second electrolyte electrode assembly that are disposed in a central portion in the stacking direction. Therefore, the dummy cells, which function as heat insulating layers, are disposed at ends, in the stacking direction, of the fuel cell stack having a skip cooling structure.